Follow-up question:
Does this setup mean that Tor will encrypt everything client side before sending through VPN - thus the VPN will never see anything but encrypted traffic? (It's my own VPN on my own VPS, but you know.. ;)

1 Answer
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Answer to your initial question:
If your client has internet access through the VPN, this should be sufficient to initiate a Tor handshake. Your VPN server should be smart enough to forward your client its own traffic.

Answer to your follow-up question:
Yes, any traffic viewable on your VPN would be encrypted.

Tor uses a process of encryption called "Onion Routing" where your computer encrypts the message multiple times based on how many relay stations it will hit on the way to its destination. Packets sent FROM your client will be encrypted multiple times and then be decrypted one layer at a time on the way to each relay station. At the final relay node, it decrypts the message entirely and sends it to the intended recipient.

On the return journey, the last Tor node in the chain re-encrypts the message and sends it back all the way through in a similar process. Each node encrypts it further until finally the host receives the message encrypted x number of times. It decrypts the message with all of the shared keys and can finally view the message.

Thanks for great answer. So, just to get it in sideways, the client packets would first be encrypted by Tor, then sent thru VPN, then out onto the Tor-network? Does that mean I get the VPN's serverside speed/bandwidth on the Tor-network, and not client-side? Or could that be configured? (Massive difference obviously.) Thanks again WB!
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knutoleMay 24 '13 at 14:07

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You got it. Once everything is established, Packets are encrypted by Tor and sent through the VPN to your server. Once at your server, it will route the traffic to the first node. Tor takes over from there. You speed and bandwidth are dictated by a bunch of different connections. Between you and your server, your server and node 1, node 1 & node 2, etc, etc, node x & destination. Then going back it's the same. So think of it broken down into a lot of different steps. You only have control over one. Since Tor is hosted by volunteers it's totally random what you end up with.
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Will.BeningerMay 24 '13 at 14:12